Merge branch 't/alsa_improvements'

Was cooking for almost two months.

* t/alsa_improvements:
  alsa: Remove pointless initialization.
  alsa_mix: Allow non-positive mixer values.
  alsa: New writer option: --buffer-time.
  alsa: Work around poll fd problems.
  alsa: Set period time.
  alsa: Also dump hardware params.
  alsa: Improve help text of --device.
  alsa: Improve documentation of struct private_alsa_write_data.
  alsa: Don't set t->error in ->pre_select().

diff --cc NEWS
index 508288ecfe94de4a36d471df39e9eb0b49f0b64a,cc9b67ad18da23606ca2167d8b1fe94da1cb4ee5..7cf5dca2f14925e45f906ca3890783375fb10e52
--- 1/NEWS
--- 2/NEWS
+++ b/NEWS
@@@ -1,35 -1,14 +1,41 @@@
  NEWS
  ====
  
 ----------------------------------------------
 -0.5.2 (to be announced) "orthogonal interior"
 ----------------------------------------------
++-------------------------------------------------
++0.5.3 (to be released) "symbolic synchronization"
++-------------------------------------------------
+ 
 -      - The new sync synchronizes playback between multiple clients.
++      - Various alsa-related fixes, mostly for the raspberry pi.
++
 +----------------------------------------
 +0.5.2 (2014-04-11) "orthogonal interior"
 +----------------------------------------
 +
 +The new sync filter, the AES_CTR128 stream cipher and the overhauled
 +network code are the highlights of this release. It also includes a
 +fair number of smaller fixes and improvements not mentioned here.
 +
 +      - The new sync filter synchronizes playback between multiple
 +        clients.
 +      - Connections between para_server and para_client are now
 +        encrypted by means of AES rather than RC4 if both sides
 +        support it. RC4 is still available as a fallback. This
 +        feature is fully transparent, i.e. no command line options
 +        are necessary, and a client linked against openssl can
 +        speak with a server linked against libgcrypt and vice versa.
        - Major cleanup of the networking subsystem.
 +      - Improvements to para_fade: the new set mode, multi-channel
 +        initial volumes, better error logging.
 +      - The man pages of para_audiod, para_filter, para_recv, and
 +        para_write contain the relevant options for receivers, filters,
 +        writers. This broke in 0.5.0.
 +      - ogg/vorbis latency improvements.
 +      - Improved user manual.
        - Minor fixes to avoid clang warnings.
  
 +Downloads: ./releases/paraslash-0.5.2.tar.bz2 (tarball),
 +./releases/paraslash-0.5.2.tar.bz2.asc (signature)
 +
  ------------------------------------------
  0.5.1 (2013-12-20) "temporary implication"
  ------------------------------------------

diff --cc alsa_mix.c
index be38e887af9babf8925bcda4d8065a79f991ff7c,0c2a1cf80725937ce87beb73bf1e08f930d50d36..c860efc8aa34d9776f52375d87c4d9cb43ad3c27
--- 1/alsa_mix.c
--- 2/alsa_mix.c
+++ b/alsa_mix.c
@@@ -148,12 -148,12 +148,12 @@@ static int alsa_mix_set_channel(struct 
        if (ret < 0) {
                PARA_NOTICE_LOG("unable to get %s range (%s): %s\n",
                        mixer_channel, h->card, snd_strerror(ret));
 -              return -E_ALSA_MIX_BAD_ELEM;
 +              return -E_ALSA_MIX_RANGE;
        }
-       if (h->pmin < 0 || h->pmax < 0 || h->pmin >= h->pmax) {
+       if (h->pmin >= h->pmax) {
                PARA_NOTICE_LOG("alsa reported %s range %ld-%ld (%s)\n",
                        mixer_channel, h->pmin, h->pmax, h->card);
 -              return -E_ALSA_MIX_BAD_ELEM;
 +              return -E_ALSA_MIX_RANGE;
        }
        return 1;
  }

diff --cc alsa_write.c
Simple merge

diff --cc m4/gengetopt/alsa_write.m4
Simple merge